1. Field of the Invention
The present invention relates to a one-way clutch of roller type used as a torque transmitting element or a back stop in a driving apparatus of a motor vehicle, an industrial machine and the like, for example.
2. Related Background Art
In general, a one-way clutch of roller type is comprised of an outer race, an inner race disposed in concentric with the outer race, a plurality of rollers disposed between an outer peripheral surface of the inner race and inner peripheral cam surfaces of the outer race and adapted to transmit torque, and springs contacted with idle rotation sides of the rollers.
With this arrangement, in the one-way clutch, the inner race is designed so as to be rotated only in one direction with respect to the outer race by means of a cam mechanism constituted by the rollers and the cam surfaces. That is to say, the inner race is designed so that it is idly rotated relative to the outer race in one direction, and on the other hand, it applies rotational torque to the outer race via the cam mechanism only in an opposite direction.
In the one-way clutch of roller type, to obtain positive engagement, rollers as torque transmitting members and accordion springs for biasing the rollers are disposed in respective pockets provided in the outer race or the inner race.
In particular, in a one-way clutch of roller type of a motor bike, since the number of rollers is small (for example, three to six), if the respective rollers are not engaged positively, a design torque capacity may not be maintained. In the prior arts, to prevent the rollers and the accordion springs from being dislodged in an axial direction, in many cases, side plate or plates is/are provided at axial one side or both sides of the one-way clutch of roller type.
For example, in Japanese Patent Application Laid-open No. 2007-64475, side plates or covers are provided on a one-way clutch of roller type, and a projection is formed on either side plate, thereby preventing accordion springs from being dislodged in an axial direction.
In order to enhance a quality of the one-way clutch of roller type, it is necessary to reduce fluctuation of a relative position of the accordion spring with respect to the outer race, and it is desired that the accordion spring is not slid against an inner diameter portion of the outer race, an outer diameter portion of a holder or a track surface of the inner race, thereby preventing the accordion spring from being damaged due to a sliding movement and/or wear. To achieve this, it is sought that the accordion spring is positively secured to a predetermined portion of the outer race.
Further, since foreign matters accumulated in the one-way clutch of roller type affect a bad influence upon engaging performance of the one-way clutch, it is desirable to remove such foreign matters. To achieve this, it is sought that the side plates are eliminated and pockets are exposed in the axial direction. Further, an inexpensive one-way clutch of roller type for a starter is needed.